Prevention of the formation of carbon in operations carried out with hydrocarbons at an elevated temperature



m 1 A MITTASCH ET AL 7.

PREVENTION OF THE FORMATION OF CARBON IN OPERATIQNS CARRIED OUT WITH HYDRQCARBONS AT AN ELEVATED TEMPERATURE Original Filed March 11. 1927 fl BYZLeir ATToRNEYs faunaler Patented Mar. 1, 1932 UNITED STATES PATENT OFFICE ALWIN MITTASOH, OB MANNHEIM, RUDOLF WIETZEL, OF LUDWIGSHAFEN-ON-THE- BHINE, AND CONRAD PFAUNDLER, OF OPPAU, GERMANY, ASSIGNORS TO I. G. FARBENINDUSTRIE AKTIENGESELLSCHAFT, OF FRANKFORT-ON-THE-MAIN, GER- MANY, A CORPORATION 01' GERMANY PREVENTION OF THE FORMATION OI CARBON IN OPERATIONS CARRIED OUT WITH HYDROCARBONS AT AN ELEVATED TEMPERATURE Original application filed March 11, 1927, Serial No. 174,694, and in Germany March 13, 1926. Divided and this application filed August 2, 1928. Serial No. 287,096.

This is a divisional application relating to subject-matter which has been divided out from our copending application Serial No. 174,694, filed March 11, 1927.

This invention relates to improvements in the prevention of the undesirable formation of carbon and soot in operations conducted with gaseous or liquid hydrocarbons or mixtures containing the same at an elevated temperature. As examples of such operations conducted with hydrocarbons at an elevated temperature may be mentioned a conversion of high boiling hydrocarbons into others of low boiling point, the transformation of gaseous hydrocarbons into liquid hydrocarbons, the distillation of hydrocarbons, the dehydrogenation of aromatic compounds, the treatment of coaly materials by extraction with solvents with or without the aid of pressure, the hydrogenation of unsaturated compounds, for example of ethylene to ethane, and operations in which hydrocarbons or mixtures containing the same are formed for example by splitting oil water from, or hydrogenating organic compounds wh ch contain oxygen, such as lphenols, extraction products of coaly materia s and the like. All such operations are hereinafter referred to for the sake of brevity as operations carried out with hydrocarbons at an elevated temperature.

We have now found that the formation of coke and soot in these said operations may be very considerably diminished or entirely prevented by adding or supplying metalloids to the metallic (and non-metallic, if any materials which come into contact wit the liquid or gaseous hydrocarbons at high temperatures, mere traces of such additions being often suificient. Boron, or its compounds, are particularly suitable for this purpose, arsenic, antimony, bismuth, phosphorus, selenium or the compounds thereof and silicon being also ap licable. All these materials are capable o furnishing volatile hydrogen compounds. Thus the hydrides of boron, arsenic, antimony, bismuth, phosphorus, selenium and silicon are of high utiligy in this process. Such additions may be e ected in a variety of ways, where employing, for example, materials, such as iron, copper and the like alloyed with boron or the like. For the construction of the apparatus it is generally suflicient, however, to coat the materials with a thin layer of substances to be added by wetting them with solutions of boric acid or treating them with gases and the like containing boron or arsenic or the like. The addition of the said metalloids may also be effected by adding to the hydrocarbons to be treated small quantities of the hydrogen compounds thereof. In some cases it may also be of advantage to mix any non-metallic substances present in the apparatus, especially insulating masses of ma nesium oxid or the like, and catalysts, with boric acid and the like, or to use for the construction of such parts substances containing metalloids as for example boron nitride, diamotaceous earth, mica and the like. The advantages of this method of working are particularly apparent in operating with liquid hydrocarbons under pressure. The said method ma also be applied,"for example, in the distil ation of hydrocarbon mixtures, followed by catalytic treatment of the vapors in the presence or absence of reactive gases.

Substances (free iron in particular) lead ing to deposition of soot should be absolutely excluded from the hot parts of the of the apparatus. It should however be noted that iron in the form of alloys such as steels containing chromium, manganese, or tungsten, and the like does not exhibit any injurious action.

According to the present invention, the substances coming into consideration as materials for the inner Walls of the reaction vessels, for feed and efliuent pipes, heat exchanging devices (if any), and the like, are more particularly the noble metals, quartz, ferro-silicon, mica, glazed or fused porcelain, aluminium, molybdenum, tantalum, chromium, and alloys of chromium free from iron, manganese, molybdenum, cobalt and the like, with or without a coating of lustrous carbon and also other materials coated with lustrous carbon, such as coal, or the like. The use of catalysts for example in the transformation of gaseous hydrocarbons into liquid hydrocarbons, is not essential, but if they are used, it has been found that all such substances are suitable as do not lead to the production of any appreciable deposition of coke or soot (if at all) namely the materials mentioned above, or silica, pumice, barium carbonate, charcoal impregnated with barium salts, boron, tungsten and the like either alone or on suitable carriers or the like, or in conjunction with other compounds.

In working with carbon monoxid or mix tures containing the same, and also in the conversion of hydrocarbons of high boiling point into others of lower boiling oint, the said method of operating with ad itions of metalloids or metalloid compounds is also a matter of considerable practical importance.

The manner of carrying the process accordin to the resent invention into practice wi be furt er illustrated with reference to the accompanying drawing, but it should be understood that the invention is not limited to the modification shown in the drawi hydrocarbon gas to be polymerized is introduced by way of a pipe A into the pressure vessel C at B. About 0.01 per cent by weight of a hydride of one of the said metalloids is admixed with the said hydrocarbon gas at A. D represents the catalyst. F is a heat re enerator through which the liquid hydrocarbons formed and in which they give elf their heat to the hydrocarbon ases entering at B. The catalyst is heated y means of the device E. The reaction products are passed from G into the separating vessel H. Li uid h drocarbon products are drawn off at The gases pass off at O and through the valve K into the separating vessel L from which a further amount of liquid hydrocarbons is drawn off at N. The gases pass off at P and may either be withdrawn from the system at Q or may be recycled by way of t e circulating pump R.

The following example will further illustrate how the said invention may be carried into practical effect but the invention is not limited thereto.

Example: A mixture of 80 percent of ethylene, 17 percent of hydrogen and 3 percent of carbon dioxide to which from 0.01 to 0.05 ercent of hydrides of silicon have been added, is passed, while under a ressure of 40 atmospheres, through a chromiumnickel tube lined with tin which contains pieces, of the size of peas, of silica gel coated with lustrous carbon by a treatment with vapors of benzene at 850 0., and which is heated to a temperature between 550 and 650 C. By condensing the vapors issuing from the tube a mixture of low-boiling unsaturated and aromatic hydrocarbons is obtained which ma satisfactorily be employed as motor fuel. f no hydrides of silicon are added to the initial gas mixture the tube is soon clogged by deposition of carbon.

What we claim is 1. A process for the prevention of an undesirable formation ofcarbon and soot in operations carried out with hydrocarbons at an elevated temperature, which comprises supplyin other than as a catalyst or a source 0 hydrogen a hydride of a metalloid selected from the group consistin of boron, arsenic, antimony, bismuth, p iosphorus, selenium and silicon to the metallic materials which come into contact with the hydrocarbons so long as they have a high temperature to thereby prevent said undesirable formation of carbon and soot.

2. A process for the prevention of an undesirable formation of carbon and soot on the metallic surfaces and non-metallic surfaces of the apparatus in operations carried out with hydrocarbons at elevated temperatures, which comprises admixing other than as a catalyst or a source of hydrogen a small amount of a hydride of a metalloid selected from the group consisting of boron, arsenic, antimony, bismuth, phosphorus, selenium and silicon with said hydrocarbons to thereby prevent said undesirable formation of carbon and soot.

3. In the conversion of gaseous hydrocarbons into liquid hydrocarbons, preventing a formation of carbon and soot on the surfaces of the apparatus with which said hydrocarbons come into contact by admixing other than as a catalyst or a source of hydrogen a small amount of a hydride of a metalloid selected from the group consisting of arsenic, bismuth, phosphorus, selenium and silicon with said hydrocarbons to thereby prevent said undesirable formation of carbon and soot.

4. In the distillation of hydrocarbons, preventing a formation of carbon and soot on the surfaces of the apparatus with which said hydrocarbons come into contact by admixing other than as a catalyst or a source of hydrogen a small amount of a hydride of a metalloid selected from the cup consisting of arsenic, bismuth, phosp orus, selenium and silicon with said hydrocarbons to thereby prevent said undesirable formation of carbon and soot.

5. In the dehydrogenation of h drocarbons, preventin a formation of car on and soot on the sur aces of the apparatus with which said hydrocarbons come into contact by admixing other than as a catalyst or a source of hydrogen a small amount of a hydride of a metalloid selected from the cup consisting of arsenic, bismuth, phosp orus selenium and silicon with said hydrocarbons to thereby present said undesirable formation of carbon and soot.

6. In the conversion of gaseous hydrocarbons into liguid hydrocarbons, presenting a formation 0 carbon and soot on the surfaces emons of the apparatus with which the hydrocarbons come into contact by admixing other than as a catalyst or a source of hydrogen a small amount of a hydride of a metalloid selected from the group consisting of boron and antimony with said hydrocarbons to thereby prevent said undesirable formation of carbon and soot.

7. In the distillation of hydrocarbons, preventing a formation of carbon and soot on the surfaces of the apparatus with which said hydrocarbons come into contact by admixing other than as a catalyst or a source of hydroen a small amount of a hydride of a metaloid selected from the oup consistin of boron and antimony wi said hydrocarfions to thereby prevent said undesirable formation of carbon and soot.

8. In the dehydrogenation of hydrocarbons, pre'ventin a formation of carbon and soot on the su aces of the apparatus with which said hydrocarbons come into contact by admixing other than as a catalyst or a source of hydrogen a small amount of a h dride of a metalloid selected from e group consisting of boron and antimony with said hydrocarbons to thereby prevent said undesirable formation of carbon and soot.

In testimony whereof, we afiix our signalfl tures.

ALWIN MITTASCH. BUDOLF WIETZEL. CONRAD PFAUNDLEB.

names 3 of the apparatus with which the hydrocarbons come into contact by admixing other than as a catalyst or a source of hydrtlilgen a small amount of a hydride of a meta 01d 6 selected from the group consisting of boron and antimony with said hydrocarbons to thereby prevent said undesirable formation of carbon and soot.

7. In the distillation of hydrocarbons, pre- 10 venting a formation of carbon and soot on the surfaces of the apparatus with which said hydrocarbons come into contact by admixing other than as a catalyst or a source of hydrofen a small amount of a hydride of a metaloid selected from the on consistinfioof boron and antimony wi sa' hydrocar ns to thereby prevent said undesirable formation of carbon and soot.

8. In the dehydrogenation of hydrocar- 20 bone, pre'ventin a formation of carbon and soot on the su aces of the apparatus with which said hydrocarbons come into contact by admixing other than as a catalyst or a source of hydrogen a small amount of a lig- 25 dride of a metalloid selected from a group consisting of boron and antimony with said hydrocarbons to thereby prevent said undesirable formation of carbon and soot.

In testimony whereof, we aflix our signatures.

ALWIN MITTASCH. RUDOLF WIETZEL. CONRAD PFAUNDLEB.

CERTIFICATE or CORRECTION.

Patent No. 1,847,095. March 1, 1932.

nuns nmnscn ET AL.

It is hereby certified that em: appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line es mm 5, for "present" read "prevent"; and line 129, claim 6, for "presenting read "preventing"; and that the said Letters Patent should he read with these corrections therein that the same ll!) custom to the record ofuthe case in the Patent Otiiee. y

Signed and sealed this 13th day of December, A. D. 1932.

M. J. Moore.

(Sell) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 1,847,095. March I, I932.

ALVIN MITTASCH ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 126, claim 5, for "present" read "prevent"; and line 129, claim 6, for "presenting" read "preventing"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent 0!! ice.

Signed a d aealed this 13th day of December, A. D. 1932.

M. J. Moore.

(Seal) Acting Conmiaeioner of Patents. 

